> Among the elaborate horses, bulls, bears and hunters, there are some other rather less captivating designs – small geometric motifs, etched onto the walls. Until now, they’ve not received much attention.
I would have expected the opposite.
Someone drawing animals and hunters could easily be explained simply by them drawing what they see everyday.
Those other things, though, are harder to explain as merely drawings of things they see.
Not hard to explain: they were simply drawing the glow discharges they saw in the sky. The growing body of theory–research isn't well known yet; for an introduction, see Peratt's groundbreaking paper from 2003:
Characteristics for the Occurrence of a High-Current, Z-Pinch Aurora as Recorded in Antiquity
I would have expected the opposite.
Someone drawing animals and hunters could easily be explained simply by them drawing what they see everyday.
Those other things, though, are harder to explain as merely drawings of things they see.